Fractional line space typewriter mechanism



Dec. 29, 1964 E. e. HOYSAK FRACTIONAL LINE SPACE TYPEWRITER MECHANISM Filed Oct. 50, 1961 INVENTOR. Edward G. Hoysok %a%%t7% ATTORNEYS United States Patent Office Patented Dec. :29, 1964 3,163,279 FRACTIGNAL LINE SEACE TYPEWRITER NECSM Edward G. Hoysak, Syracuse, N.Y., assignor to SCM Corporation, a corporation of New York Filed Oct. 30, 1961, Ser. No. 148,508 11 Claims. (Cl. 197-114) This invention relates to improvements in typewriter line space mechanisms and, more particularly, to improvements in the control and actuation of the line space pawl to engage the teeth of the platen ratchet in electric typewriters and the like.

The conventional line space pawl mechanism first guides the pawl about the outer periphery of the platen ratchet before allowing the pawl to engage the ratchet teeth to vertically line space the work sheet. 'United States Patent No. 1,817,252, issued August 4, 1931, to G. G. Going, for Typewn'ting Machine contains an illustration'of such a line space mechanism. This structure has a definite disadvantage in power operated typewriters. With the usual rapid action of the pawl as it follows the arcuate path about the ratchet, even though it is spring urged to engage the ratchet, it tends to either engage a ratchet tooth preceding, or slip over and engage a tooth following the intended tooth to be engaged. This difficulty is presently overcome by making several precise adjustments.

. Since the member that guides the pawl about the outer periphery of the ratchet is adjustable for varying the number of vertical line spaces for each stroke of the pawl precise adjustments are essential to accurately engage the pawl withthe proper ratchet tooth.

This disadvantage is overcome by providing a fixed limit of ratchet wheel advancing pawl travel, a selectively adjustable limit of pawl return to thereby selectively vary the over-all pawl .travel during each stroke and concomitantly the number of line spacesper pawl stroke. The present invention provides an improved mechanism of this latter type which is more readily, positively, and flexibly adjusted than those heretofore available.

It is therefore the object of this invention to provide an improved line space mechanism that overcomes the disadvantages by having the pawl first directly engage the ratchet teethbefore the pawl starts rotating the ratchet.

This completely avoids the possibility of the pawl engaging the improper ratchet tooth. The necessity of the precise adjustments required because of the adjustable guide member is eliminated by the invention in that the adjustable member carries the pawl as it is positioned for the variable line space setting:

More specifically the objects of this invention are to provide an improved selectively variable return stroke line space mechanism for typewriters and the like in which:

(1) The selectable line spacing may be any of a plurality of whole number line spaces, a fraction of a line space or a combination thereof so that exponents and subscripts may bereadily and properly uniformly positioned;

(2) The line space amplitude selection is positively retained against inadvertent maladjustment; and

(3) The line space amplitude selection is positively retained against inadvertent maladjustment yet readily manipulatable by finger pressure.

These and other objects of this invention will become more fully apparent by reference to the appended claims and as the following detailed description proceeds in refer- FIGURE 1 showing the relation of the pawl, earn and ratchet in their normal inoperative position and taken substantially along the line 2-2 of FIGURE 3;

FIGURE 3 is a view of the mechanism of FIGURE 1 taken substantially along the line 3-3 of FIGURE 2; and FIGURE 4 is a reduced view taken substantially along the line 44 of FIGURE 3 showing the relationship of the finger control, cam carrier and the adjustable matching teeth.

As indicated above, the line space mechanism of the present invention is of the selectively variable return stroke type. As is best shown in FIGURES 1 and 2, the line space mechanism comprises a ratchet wheel 10, conventionally fixed in coaxial relation to the left end of the platen (not shown), and a pawl 12 having a ratchet wheel engaging portion 14 and pivotly mounted at 16 upon a pawl carrier 18 journaled coaxial with ratchet wheel 10. Ratchet wheel 10 is fixed to a stub shaft 20 that extends through and is journaled by a bushing 22 fixed to the left side of frame 24 of the conventional carriage. Pawl carrier 18 is pivotlly mounted upon the exterior of bushing 22 intermediate ratchet wheel 10 and side frame 24.

Pawl carrier 18 is resiliently biased in a counterclockwise direction as viewed in FIGURE 2 by a torsion spring 26 (see FIGURE 1) toward a stop position selectively positionable by the typist as will be explained presently.

Pawl carrier 18 is actuated in a clockwise direction about the axis of bushing 22 in opposition to spring 26 by the torque exerted thereon as the result of downward ten sioning of a tape 28 conventionally pivotly connected thereto at pin 30 by a clip 32. Tape 28 is the carriage return tape. The typewriter is equipped with a conventional carriage return clutch that automatically line spaces the work sheet before the carriage is returned. The line space mechanism is activated by carriage return tape 28 which is directly connected to and tensioned upon engages ment of the carriage return clutch (not shown). The clip 32 is rigidly connected to tape 28 and is pivotly connected to the pawl carrier 18 by pin 30 and is retained by a keeper (not shown).

v Pawl 12 has a portion lying generally parallel to the pawl carrier 18 which is somewhat Z-shaped as viewed from above FIGURE 2. It has a first portion 34 lying behind the portion 36 of carrier 18 and pivoted at 16 to carrier 18, an intermediate portion 38 extending laterally through the notch 40 between portions 36 and 42 of car- 12 carries at its top the ratchet wheel engaging portion 14 and at its rear face a rearwardly projecting stud 46 journaling a roller 48 which, as will be explained presently, cooperates with a selectively positionable cam to estab! lish the limit of return stroke of the pawl 12.,

Pawl 12 is resiliently biased in a counter-clockwise direction about its pivot 16 as viewed in FIGURE 2 by a torsion spring 59 wound about a stud 52 coaxial with pivot 16,'fixed at one end by portion 54 thereof overlapping the edge 56 of carrier 18 and engaging at its opposite end a stud 58 fixed to portion 44 of pawl 12. As paw carrier 18 is pivoted clockwise about shaft 20 by tensioning of tape 28, roller 48 on the end of the pawl which is biased by spring 50, rolls downward along cam surface 88 so that the ratchet engaging pawl tooth 14 moves into the teeth of the ratchetwheel 10 directly toward'the bottom portion between the ratchet wheel teeth. This abrupt and substantially radial movement of the pawl engaging tooth 14 is a direct result of the steep drop of the cam face 88 along which the pawl roller 48 drops as the leading end of the pawl 38 is advanced by continuous clockwise mo tion of pawl carrier 18. Thus the initial motion of pawl 38. is an abrupt counterclockwise pivot movement about the pawl pivot 16 which results in a materially greater magnitude of movement of the pawl engaging tooth 14 toward the axis of the platen axle 20 than is the magnitude of the concurrent angular movement of the pawl engaging tooth 14-.relative to the teeth of the ratchet wheel. As soon as direct movement'of the pawl engaging tooth 14 into engagement with the ratchet teeth is. terminated by bottoming between teeth the continuing clockwise motion of the pawl carrier 18 can thenresult only in angular movement of the pawl 12 so that the pawl'tooth 14 will now move only angularly along with the carrier;

Such movement of thepawl tooth itself results in .a direct full engagement with the desired ratchet tooth before any 7 Retainer member 96 is "resiliently biased in a clockwise direction as viewed in FIGURES 1 and 4 about the axis of shaft 62 by a coil spring 98 tensioned between member 96 and a spring stud 99 on plate 24. Retainer member 96 has a laterally offset portion 100 formed with a toothed segment 102. When retainer member 96 is in its normal position shown in FIGURE 4, segment 102 meshes with a toothed segment 104 on plate. 76 of stop assembly 74 to positively prevent pivotal movement of stop assembly 74 about the axis of ratchet wheel 10.

Actuator 92' has a laterally projecting pin 106 fixed thereto which projects between the upwardly projecting angular movement of the pawl tooth 14is effective-against the engaged ratchet toothto cause rotation of the ratchet wheel and insuresproper tooth selection before advancement of the ratchet wheel 10. p The limit of travel of carrier 18, pawl 12 and ratchet wheel in a clockwise direction in response totensioning of tape 28 incident to initiation of carriage return action is established by the engagement of theend pawl portion 14. with a stop 60 '(FIGURE 1) disposed in its path. Insofar as the typist is concerned, stop '60 is fixed. Actually it is adjustable by maintenance personnel. Stop 60 is fixed to a shaft 62 journaled in axially fixed relation between carriage side frame 24 and a parallel'bracket 64 fixed relative to side frame 24 by screw 66 The "angular position of shaft '62 and-stop 60about' the axis'of shaft 62 is controlled by an arm '68 fixed to shaft 62in adjacent parallel relationto frame 24,, and a screw70" projecting through an arcuate slot 72 in 'plate 24 and threadedly connected to ar-m68 to clamp arm68 to plate 24 in the selected angular position. This'adjustm'ent is eflected at the factory tofgassure proper .terminalof the platen after each line space operationde'spite dimensional variations in parts sizes within accepted tolerances. It may also be made by maintenance personnel to adjust for any wear ofthe parts involved.

The limit of the. return stroke'of the pawl carrier 18 under the influence 'of spring 26 an'dthe disengagement i of pawl'12 from ratchet wheel 10 at the end of the'return stroke of carrier 18 is selectively controlled byselectively positioning a stop assembly 74. Stop assembly 74 -comcessivelydisengage pawl 12 from its ratcheting iengagea ment with ratchet wheel '10 and to arrest rota-tion of pawl carrier 1-8 at the'end of the pawl and pawl carrier return stroke. Referring to FIGURE 2 as carrier 18 and pawl 12 are restored in a counter-clockwise direction under the influence of spring 26, ro1ler48 engages cam'fsurfaces 88 thereby causing pawl 12 to pivot clockwise about pivot 16 relative to carrier 18 '-as carrier 18. continues to pivot counter-clockwise about the axis of ratchetwheel 10. P'awllZ pivots in this manner until'the roller'48 en.- gages the cam surface 86. This is theposition shown in 'FIGURE 2. In this position further counter-clockwise movementof carrier 18 isblocked.

The typist may select any of a pluralit-yof discrete positions for plate 76 of stop assembly74 by manipulation of actuator 92 solely by finger. pressure. The angular position of cam 80'relative to plate 76 in each of these positions is adjusted at the factory and by field maintenance personnel by; the screw and slot connection 8284.

The actuator 92 is pivotly mounted by a pivot stud 94 upon a retainer member 96 pivotly mounted on the end of the shaft 62 projecting through. carriage. end plate 24.

return clutch (not shown).

arms 108 and'110 of the. plate 76of' stop assembly 74 which form alguide slotr111 for pin 106. So long as, the toothed segments 102 and 104 remain engaged, finger pressure upon the concave serrated portion 112 of actuator 92 merely results in depression of actuator 92 in a path determined by the engagement of pin 106 withslot 111. Such depression of actuator 92 pivots retainer member 96 counter-clockwise as is 'viewedin FIGURES 1 and 4 to disengage segments 102 and 104. At the I point of disengagement of segments 102' and 104, pivot stud 94 is substantially eoaxially aligned with the axis of ratchet wheel 10. In this position,actuator92-canbe pivoted by finger pressure about the axis of pivot stud 9,4 to thereby pivot return stop assembly 74 about'the axis of ratchet wheel 10 to thereby effect the selection. of the amplitude of line spacedesired, The spacing of the.

teeth of segments 102 and 104 is such'that-the over-all travel of the ratchet wheel selected may be either a whole .number of line spaces, a fraction of a line space .or a combination thereof.

line spaces for eachstroke of the pawl 12 maybe selected.

Forexample: 1, 1%, 2, 2 /2, or 3 To summarize, the operation of the disclosed embodiment of this inventionfollows. The depression of the carriage return button (not'shown) engages the carriage downward, which-pivots pawl carrier 18 clockwise about bearing bushing 22. The clockwise movement of pawl carrier 18.,pivots pawl. mounting stud .16 clockwise and, since roller 48.is biased against cam surface-88 by torsion spring 50, pawl.12 moves counter-clockwise and directly engages a tooth ofplaten ratchet wheel 10. As soon as the pawl has bottomed into a tooth, the continuing clockwise motion of pawl carrier 18 causes pawl 1210 rotate ratchet'wheel '10 clockwise until pawl 12,1imits againststop'60. Stop 60 is rigidly assembled to shaft62.'

Adjuster arm 68-is rigidly assembled to shaft 62- having a rearward extension supported byscrew inan arcuate aperture 72. The pivotal movement of adjuster arm 68 provides arotational adjustment forstop 60which permits the proper spacing of the platen ratchet wheel 10.

When the carriage return clutch is released at the end of the carriage return movement. by the conventional means of the left marginstop actuating a releasebracket,

torsion spring-26,. which is fixed at 'onc'end',through aperture '114-in carrier-18 and at the'other end" to spring stud 116. on plate .76 of stop assembly 74, biases pawl carrier 18- counter-clockwise about bearing bushing 22 until its movement isterminated by roller 48 contactingcamsura face 88. The pawl 12 is then biased upward in a clockwise direction inopposition tothe force of 'spring50'by the stronger spring 26 to the normal. inoperativeposition shown in FIGURE 2.

To effect line space amplitude selection, the actuator 92, having a slightly raised ooncaveserrated portion112,

is pivotably mounted on the forward extension of retainer 96 .by stud 94. The spring 98 is connected to the rearward extension of retainer. 96 and to a spring anchor stud 99 (FIGURE 4) that is riveted to the outside of left carriage end frame plate 24. The lateral extension of re-.

' tainer96extends through aperture'118' in plate '24 and downward such that itsv toothed segment .102? is urged under the .bias of spring 98 into engagement with the matching toothed segment stop assembly 74.- Segment The clutch pulls tape .28

104 has more teeth than segment 102 and the teeth are so spaced to provide the variable settings of 1, 1 /2, 2, 2 /2, and 3 vertical line spaces. The projecting pin 106 as an integral part of actuator 92 extends across carriage end plate 24 and is seated in the slot 111 between extensions 108 and 110 of cam carrier plate 76.

To adjust the vertical line space setting, the depression of actuator 92 by finger of thumb pressure atrportion 112 pivots retainer 96 counter-clockwise about shaft 62 which disengages segment 102 from segment 104. Actuator 2 is then either pivoted clockwise for fewer spaces per stroke of pawl 12 or counter-clockwise for additional spaces. Upon releasing actuator 92, spring 98 biases retainer 96 clockwise until segment 102 again engages segment 104.

To adjust from the normal single space setting to any of the remaining settings, the counter-clockwise movement of actuator 92 causes pin 106 to pivot stop assembly 74 counterclockwise. Since spring 26 biases pawl carrier 18 and therefore pawl 12 to its normal inoperative position, which is determined by roller 48 contacting cam surface 86 and 88; pawl carrier 18 follows the counter-clockwise movement of stop assembly 74. This provides the advantage that the pawl 12 is always directly above the ratchet tooth to be engaged and results in a constant bias by spring 26 in the home position of pawl 12 regardless of the selected position of actuator 92.

The structure of this mechanism reduces the number of adjustments from the conventional structures and simplifies the remaining adjustments.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. I

What is claimed and desired to be secured by United States Letters Patent is:

1. In a typewriter, a platen line space mechanism embodying:

a platen mounted rotatable ratchet, a coaxially pivoted cooperating selectively variable return stroke ratchet advancing pawl means including a pivotally mounted pawl,

stop means mounted for pivotal movement about the ratchet rotation axis for varying the amplitude of the pawl return stroke,

means for positively retaining said stop means in its selected position, and

an actuator connected to said stop means and said retaining means, and means mounting said actuator for movement in a first path to effect engaging and disengaging movements of said retaining means and for movement in a second path to move said stop means while said retaining means is disengaged.

2. The combination defined in claim 1 wherein said retaining means embodies:

a first toothed sector on said stop means and coaxial with said stop means pivot axis,

a member pivoted about an axis parallel to said stop means pivot axis and having a second toothed sector thereon selectively engageable with the teeth of said first toothed sector, and

means biasing said sectors into meshing engagement.

3. The combination defined in claim 2 wherein said actuator is pivotally mounted on and m'oveable with said member so that said actuator can be manipulated to move said member to disengage said first and second sectors and manipulated to move relative to said member to move said stop means.

4. In a typewriter,

a variable return stroke line space mechanism,

means for controlling the amplitude of movement of said mechanism, which means is selectively adjustable through a series of equal steps, said controlling means including:

a positive self locking retainer mechanism biased to its locking condition and a single member, manipulatable under finger pressure to disengage said retainer mechanism against its bias and to etfect the selective adjustment of amplitude of movement of said line space mechanism during disengagement of said retainer mechanism.

5. In a typewriter, a platen line space mechanism embodying:

(a) a platen mounted rotatable ratchet,

(b) a coaxially pivoted cooperating selectively variable return stroke ratchet advancing pawl means compris- (1) a plate pivotally mounted coaxial with said ratchet, (2) a pawl pivot-ally supported on said plate, (3) means biasing said pawl toward engagement with said ratchet, and (4) an abutment member on said pawl, (0) stop means, including a cam. engagea'ble by said pawl abutment memberto define the limit of the pawl return stroke and having a cam surface thereon to be engaged by said pawl abutment member to cause radial movement of the ratchet engaging portion of said pawl relative to said ratchet at the limit of the pawl return stroke, and Y (d) means biasing said 1 late to move said pawl into engagement with said cam. 6. In a typewriter, a platen line space mechanism embodying:

(a) a platen mounted rotatable ratchet and (b) a cooperating selectively variable return stroke ratchet advancing pawl means including (1) a pawl carrier pivotally mounted coaxially relative to said ratchet, (2) a pawl having a ratchet engaging pawl tooth, (3) means pivotally mounting said pawl on'said carrier eccentric to the axis of said ratchet, and (4) means enabling shifting of said pawl aboutv its pivotal mounting means relative to said ratchet at the return limit position of the pawl stroke so that the pawl tooth moves abruptly in a pathhaving a materially greater increment relative to the axis of said ratchet, into and out of bottoming engagement with the teeth of said ratchet, than isthe concurrent angular movement of the pawl tooth, comprising.

(a) an adjustable combination pawl retraction and return limit stop cam, and

(b) v a cam follower member fixed on said pawl and adapted to cooperate with said cam to accomplish both the functions of limiting the retract movement of the pawl and of causing the pawl tooth to shift into and out of engagement with said ratchet.

7. A platen line space mechanism as defined in claim 6, wherein said means pivotally mounting said pawl on said carrier comprises a pivot means, pivotally fixing a portion of said pawl on said carrier on an-axis eccentric to the ratchet axis, and said portion of said pawl is disposed angularly ahead of said pawl tooth in the ratchet advancing direction so that said pawl tooth is pulled by said carrier to step said ratchet.

8. A platen line space mechanism as defined in claim 7, wherein said cam follower member is fixed on another portion of said pawl which is disposed angularly behind said pawl pivot portion and is located a further distance from said means pivotally mounting said pawl than the distance between said pawl tooth and said means pivotally mounting said pawl. v

- 9. -A platen line space mechanism as defined in claim 8,

where the movement of said cam followermember during engagement movement of saidpawl tooth, relative to said ratchet, hasan angular component of movement relative to the ratchet axis which is opposite to a ratchet advancing movement. t o 7 10. A typewriter platen line space mechanism as defined in claim 6 including: means mounting said combination pawl retraction and return limit stop cam for pivotal movement about the ratchet rotation axis to enableselective variation of the amplitude of the pawl return stroke.

1 1. A typewriter platen line space mechanism as defined References Cited in the file of this patent UNITED STATES PATENTS Vincent Jan. 11, Norine Apr. 29; Cnnnrine May 1, Britten June 29. 

1. IN A TYPEWRITER, A PLATEN LINE SPACE MECHANISM EMBODYING: A PLATEN MOUNTED ROTATABLE RATCHET, A COAXIALLY PIVOTED COOPERATING SELECTIVELY VARIABLE RETURN STROKE RATCHET ADVANCING PAWL MEANS INCLUDING A PIVOTALLY MOUNTED PAWL, STOP MEANS MOUNTED FOR PIVOTAL MOVEMENT ABOUT THE RATCHET ROTATION AXIS FOR VARYING THE AMPLITUDE OF THE PAWL RETURN STROKE, MEANS FOR POSITIVELY RETAINING SAID STOP MEANS IN ITS SELECTED POSITION, AND AN ACTUATOR CONNECTED TO SAID STOP MEANS AND SAID RETAINING MEANS, AND MEANS MOUNTING SAID ACTUATOR FOR MOVEMENT IN A FIRST PATH TO EFFECT ENGAGING AND DISENGAGING MOVEMENTS OF SAID RETAINING MEANS AND FOR MOVEMENT IN A SECOND PATH TO MOVE SAID STOP MEANS WHILE SAID RETAINING MEANS IS DISENGAGED. 